Embodiments of the present invention relate to an optics arrangement and to a method for optical sampling of an object plane comprising a multi-channel imaging system.
Further embodiments of the present invention relate to an ultra-flat illumination module for multi-aperture imaging systems.
According to known technology, multi-aperture imaging systems or multi-channel imaging systems may be used for optical sampling of an object plane. A known multi-aperture imaging system, as is exemplarily described in DE 10 2009 047 361 A1, allows optical image recording of an extended object field at a high spatial resolution and an extremely short length with operating distances in the range of some millimeters. In addition, the arrangement allows magnifying the object field size considered, without an axial extension of the optical setup. This is done using an increased number of optical imaging channels.
However, due to the miniaturized implementation of this known multi-aperture imaging system and the short operating distances (distance between object and optics), illuminating the object field sufficiently is difficult in the case of incident light illumination (such as, for example, when considering non-transparent and non-luminous objects). In the case of lateral incident light illumination, the large lateral extension desired results in large angles of incidence of the illumination light and a highly inhomogeneous illumination situation. Confocal illumination, as is usual in microscopy, by the imaging lens cannot be implemented technically, or only with great expenditure and at the expense of the length, due to the miniaturization of the imaging system known.
Conventional flat illumination elements (such as, for example, arrangements for display backlighting by micro-structured plates or films) are sufficiently thin, however they influence the optical path in the multi-aperture imaging optics and, consequently, cannot be used here.
Different ways of implementing direct light illumination are described in known technology. Known variations exemplarily base on a lightguide including different coupling-out mechanisms. The different coupling-out mechanisms exemplarily include coupling out by means of bumps or reflecting parts, coupling out by means of holograms or utilizing polarization effects.
Coupling-out by means of bumps or reflecting parts is, for example, described in U.S. Pat. No. 6,734,929 B2, U.S. Pat. No. 6,806,922 B2 and DE 102 44 444 A1. Coupling-out by means of bumps or reflecting parts in accordance with U.S. Pat. No. 6,734,929 B2 and U.S. Pat. No. 6,806,922 B2, however, is not suitable for (multi-aperture) imaging optics since illuminating elements in the optical path would impede imaging. Additionally, coupling-out by means of bumps or reflecting parts in accordance with DE 102 44 444 A1 is of disadvantage in that the bumps or reflecting parts are located directly in the optical imaging path close to the entrance pupil of a CCD camera. This results in a limitation to relatively large diameters of the entrance pupils (large optics). This is why the variation described in DE 102 44 444 A1 is not suitable for miniaturized imaging systems, such as, for example, multi-aperture imaging optics or micro-optics.
Coupling-out by means of holograms is, for example, described in U.S. Pat. No. 5,465,311, in U.S. Pat. No. 5,515,184 and in U.S. Pat. No. 6,429,913 B2. The disadvantage of this variation is that having holograms in the optical path would impede imaging. In addition, coupling-out by means of holograms in accordance with U.S. Pat. No. 5,465,311, U.S. Pat. No. 5,515,184 and U.S. Pat. No. 6,429,913 B2 is characterized by a marked dispersion behavior. This is why this variation is unsuitable for illuminating using spectral broad-band (white) light.
Making use of polarization effects is, for example, described in U.S. Pat. No. 6,750,996 B2 and in U.S. Pat. No. 7,027,671 B2. The disadvantage when utilizing polarization effects in accordance with U.S. Pat. No. 6,750,996 B2 and U.S. Pat. No. 7,027,671 B2 is that, with this variation, what results is a differing coupling-out efficiency for the regular and the irregular direction of polarization due to the difference in the index of refraction in birefringent media.
Conventional incident light illumination in microscopes by means of a beam splitter also represents known technology. Here, laterally incident illumination light is redirected by beam splitter cubes or cuboids. However, this conventional technology is not suitable for miniaturized imaging systems and objects distances of only a few millimeters, which at the same time have extended object fields of several square centimeters, since the thickness of the beam splitter is in scale with the area to be illuminated. This counteracts axial miniaturization.
A general problem is that, in known technology, there is no known concept which unites incident light illumination with multi-channel imaging of a close object field of lateral extensions, i.e. with a small distance of the object field to an optics arrangement, with a high image quality and a small structural height of the optics arrangement.
Consequently, it is the object of the present invention to provide a concept which allows incident light illumination for optical multi-channel imaging of a laterally extending close object field at a higher image quality and, at the same time, a smaller structural height of the optics arrangement.